Film and containers made of inexpensive polyethylene or polypropylene are common packaging materials for food, clothing, and industrial products. These packaging materials, when discarded, cause environmental pollution because they are not readily degraded by light or heat.
To address the problem, copolymers of ethylene and carbon monoxide have been proposed as substitutes for polyethylene and polypropylene, and these copolymers are used commercially on a moderate scale owing to their low price, good processability, and high photo-degradability.
One disadvantage of the ethylene/carbon monoxide copolymer is that when the copolymer is in the form of, for example, a 30 micron thick film and it is exposed to sunlight for a couple of months, it readily breaks into small pieces. On the other hand, the copolymer, when it is in the form of a thick-walled blow molded container, takes more than a year to degrade completely.
Another disadvantage of the ethylene/carbon monoxide copolymer is that it is similar in properties to high pressure polyethylene and hence it has such poor heat resistance that it cannot be used as packaging material for products which are exposed to high temperature in their packaged form.